DC DC Power module selection guide

1. Determine the specifications of the power supply:

In accordance with the requirements of customers to confirmed use of standard typical

modules or customization.

First step: Selection dimensions:

The power module should be reserved enough space to consider dissipate for heat

Interference of signal acquisition and effect of other circuit components.So need take into

size 、cost and reliability etc.

Second step: whether need isolation:

Isolation characteristics refer that the input and output of the module are independent(Not

altogether) power. In the industrial bus system, Safety isolation in the face of harsh

environment (lightning, arc interference);in mix circuit. could be achieved noise isolation of

sensitive analog circuit and digital circuit . Also can be voltage conversion in multi voltage

power supply system.

Third step :choose type of power module

Please confirmed input is AC or DC ,if it is AC ,choose AC to DC converter ;if it is DC , use DC

to DC converter.

Fourth step: Determine output current or output power.

The load current is the key to determine output power, meanwhile and directly affects the

reliability and price of the module. The Power module is best applied to 30%-80% of total

load. Too big maybe lead to loss money, too small maybe lead to low reliability.

Please note: If supply power for optocoupler and relay or RS232/485、CAN bus voltage

reference, may be occur small of load current or no load application. Recommended adding

dummy load to improve reliability of power module. If there is a large load current instability

or wide load changes range. The dummy load need choose 10%-100%,avoid light load or

over load application.

At the high temperature. Power module should be reducing Rating to use. Could choose to

reduce 30%-40% power reducing Rating and Priority to choose more big size.

The fifth step: According to the input voltage range to choose our products series.

1) 3.3V、5V、9V、12V、15V、24V input voltage range is 10%,if you need Non regulated output,

please choose DY series; if you need high isolation, please choose GDY series, typical

isolation is 1500V,high isolation is 3000V;if you need regulated output, please choose

WDY series

2) 5V（4.5-9V） ，12V（9-18V） ，24V（18-36V） ，48V（36-75V）input voltage range

is 2:1,please choose KW series.

24V（9-36V） ，48V（18-75V） 、110V（40-160V）input voltage range is 4:1, please

choose KH series.

For example: 24V industrial bus power supply; 48V communication bus power supply;

110V railway power supply;220V transformer-rectif output and kinds of batteries, lithium

batteries, dry batteries and long distance transmission and so on, please choose KH

series. If face more than output 3W power module, in order to improve efficiency ,advise

choose KW or KH series.

The sixth step: According to the type of load to select suitable the power module.

1) output voltage is determined by the type of load circuit, such as typical digital circuit,

amplifying dc or low frequency signal working, RS232/485、CAN bus etc(not high

requirements accuracy place), better choose non regulated output series module(DY

series).But if need high accuracy and low ripple , better choose regulated output series

or wide input series (WDY ,KW ,KH series).

2）Under meeting cost and efficiency conditions, could consider non regulated series

power module and linear voltage regulator used in combination.

When the load has positive and negative voltage or multi voltage supply demand. Can be

considered positive negative output or dual and multi output, as far as possible to

reduce the number of output. Bigger output power and higher accuracy as the main

output, determine the voltage accuracy requirements of the subordinate output, so that

the module design more reliable to meet the requirements

3）Typical output voltage including:3.3V，5V，9V，12V，15V，24V，±5V，±12V，

±15V etc

4）if you need high accuracy of the output and low the ripple(typical 100mV),maybe lead

to cost large increase .

As far as possible to choose typical power module, this way could meet purpose for the

low cost, mature technology, reduce the R&D of resistance and save time etc .

If you need EMC、UL 、CE certificate, please contact our sales.

Yaohua power technology Co.,ltd

www.yh-converter.com

Email:sales@yh-converter.com